Conventionally, various interfaces and configurations have been developed as operation detecting units of communication apparatuses. For example, there is a technique in which a communication apparatus is provided with a rotary dial-type input device, wherein a cursor displayed on a display unit is moved in accordance with the amount of rotation of the rotary dial-type input device (refer to Patent Document 1). However, with such a conventional technique, the use of a “rotary dial” that involves physical and mechanical rotation is likely to cause malfunctions, failures and the like due to mechanical attrition and the like, giving rise to problems such as the need for performing maintenance on an operation detecting unit, a short period of endurance, and the like.
In consideration thereof, techniques have been proposed in which a touch sensor is used as an operation detecting unit that does not involve physical and mechanical rotation (refer to Patent Documents 2 and 3). The proposed techniques include sequentially positioning a plurality of touch sensor elements, detecting an operation involving movement based on contact detection by each of the touch sensor elements, and performing selection operation control in which a selection choice is selected from a plurality of selection choices in accordance with the detection results.
In addition, a touch sensor is known which includes an operating unit, an oscillating unit that outputs an oscillation signal, and a detecting unit that detects an oscillation signal outputted from the oscillating unit, wherein an operation on the operating unit is detected based on detection results of the detecting unit which vary in association with the operation (refer to Patent Document 4).    Patent Document 1: Japanese Patent Laid-Open No. 2003-280792    Patent Document 2: Japanese Patent Laid-Open No. 2005-522797    Patent Document 3: Japanese Patent Laid-Open No. 2004-311196    Patent Document 4: Japanese Patent Laid-Open No. 2000-156631